Several types of conventional prune pitting apparatus are described in U.S. Pat. No. 3,556,281, issued Jan. 19, 1971, and in U.S. Pat. No. 5,870,949, issued Feb. 16, 1999.
In operation of a conventional prune pitting apparatus, prunes (or other articles to be pitted) fall from a hopper onto holders. A conveyor translates the holders around a closed processing path. Each holder defines at least one pocket, and typically it defines a row of four pockets (or another small number of pockets). Each pocket is configured to be closed (to grip a prune within the pocket) and opened (so that no gripping force is exerted on a prune with the pocket) at different points around the path. Each pocket is closed and opened by force exerted by cams on the holders as they translate past the cams.
Each holder includes a top (or “upper”) chuck plate shaped to guide a prune into each pocket defined by the holder. Typically, each holder also includes a pitting cup (sometimes referred to as a pitting “rubber”) at the location of each pocket, and the top chuck plate is shaped to guide a prune onto the pitting cup, as the holder translates past a prune loading station. During operation, the conveyor translates each holder past the prune loading station, and the conveyor then translates each holder past an excess fruit removal assembly to remove excess prunes (prunes not properly seated in pockets) from the holder while leaving one prune seated in each pocket. The excess fruit removal assembly is typically implemented as a paddle wheel (or set of paddle wheels), which sweeps across the cup(s) of each holder.
After translating the holders past the excess fruit removal assembly, the conveyer translates the holders to a pitting knife assembly (which pits prunes as they are gripped within the pockets), and the pitted prunes are then ejected from the pockets.
However, conventional holders have been configured in such a way that there is a significant risk that excess prunes (prunes not properly seated in pockets) can remain lodged (e.g., can be stuck) on a holder even after the holder is translated past an excess fruit removal assembly. Although it is undesirable for an excess prune (a prune not properly seated in a pocket) to be carried by the holder to the pitting knife assembly, conventional prune pitting apparatuses have been subject to significant problems (during operation) due to the frequent occurrence of incidents in which excess prunes are carried to the pitting knife assembly.